Utility trucks may have many compartments spaced around the truck, with each compartment having its own outside door and its own key-operated door lock. When a worker drives the truck to a worksite, he may have to go around the truck and use a key to unlock perhaps six doors to enable ready access to all equipment. When the worker leaves the truck to go to lunch, a restroom, or another site, he must go around the truck and use his key to lock all six doors, and later unlock them. A single control in the truck cab which locks and unlocks all access doors makes truck usage more convenient, and such an electrically-operated lock system can be installed at the factory. However, it can be expensive to retrofit existing trucks, largely because it can be difficult to install new lock mechanisms that can be electrically or key-operated, in place of the existing key-operated lock device. A method and apparatus which enabled a low cost conversion of each door lock to one which was both electrically and key operated, would be of considerable value.